In a wireless power transfer system energy can be transmitted from a power source to a load without the need for an electrical contact between both. Possible applications are the charging of electronic devices, but also for instance realizing illumination panels. Capacitive or inductive technologies are possible implementations for wireless power transfer. In wireless power transfer, power efficiency is a very important parameter.
For large area illumination emission surfaces based on light emitting diode (LED) sources nowadays technologies such as 2D attachment on large sheets of flexible substrates, combining multiple LED-strips in parallel, and alike, are required. WO 2013/024406 describes a transparent capacitive wireless powering system, which may for instance be used for powering lighting elements such as LEDs, LED strings, a lamp etc. The system disclosed comprises a pair of receiver electrodes connected to a load through an inductor, and a transparent infrastructure having at least a first layer of a non-conductive transparent material, and a second layer of a conductive transparent material coupled to each other. The second layer is arranged to form a pair of transmitter electrodes, wherein the pair of receiver electrodes are decoupled from the second layer, thereby forming a capacitive impedance between the pair of transmitter electrodes and the pair of receiver electrodes. A power signal generated by a driver is wirelessly transferred from the pair of transmitter electrodes to the pair of receiver electrodes to power the load when a frequency of the power signal substantially matches a series-resonance frequency of the first inductor and the capacitive impedance.
There is still room for improvement in creating free form (both in size and in surface topography) large area illumination products.